Incinerator

ABSTRACT

This invention comprises a smokeless, highly efficient incinerator which is economical to manufacture and is particularly adapted for burning out steel barrels to clean the same for reuse. An elongated, cylindrical steel chamber is supported horizontally and defines a passageway through which the empty steel barrels are passed. A conveyer which is driven in any suitable manner is provided for carrying the barrels through the chamber at a predetermined speed to enable them to completely burn out. Gas jets are provided for starting the fire within the chamber, and an alternating series of oil nozzles spray oil into the chamber to keep the fire burning. Novel means in the form of an adjustable air nozzle array is arranged to direct the air partly into the chamber as required to provide a recirculating action of the flame pattern and a fire of relatively low temperature. The cylindrical chamber is provided with an open slot along the full length of its upper surface over and through which the air stream is directed by a plurality of nozzles spaced along the length of the cylinder. By adjusting the air streams partly into or out of the cylinder the flame may be kept clean and smoke-free. Sensors are provided to monitor combustion conditions and to actuate the various adjustable control devices hereinafter described and thus to stabilize and control combustion for smoke-free operation of the device. Air curtains are provided at each end of the chamber so that the barrels may enter and leave the chamber with a minimum of smoke emission from these openings. An air lock could be provided with double doors at the entrance and exit openings to eliminate smoke emission and to minimize disturbance of the combustion process within the chamber.

. United States Patent Parker [451 Apr. 25, 1972 [54] INCINERATOR Paul W. Parker, Newburyport Turnpike, Rowley, Mass. 01969 [22] Filed: Apr- .27, 1970 21 Appl.No.: 31,921

[72] Inventor:

[52] US. Cl. ....ll0/8 C, 1 10/18 C, 263/50 [51] Int. Cl. ..F23g 5/12 [58] Field ofSearch ..l34/2, l9; 263/5, 50; 110/8,

110/8 A, 8 C, 18,18 C

[56] References Cited UNITED STATES PATENTS 3,163,134 12/1964 Stratford ..1 10/18 2,822,160 2/1958 Walpole... ..263/5 3,498,240 3/1970 Trott 110/18 2,592,491 4/1952 Toepel... 10/8 2,965,051 12/1960 Kocee.... 110/18 3,200,776 8/1965 Simpson ..263/50 Primary Examiner-Kenneth W. Sprague Attorney-Robert R. Churchill 57 ABSTRACT This invention comprises a smokeless, highly efficient incinerator which is economical to manufacture and is particularly adapted for burning out steel barrels to clean the same for reuse.

An elongated, cylindrical steel chamber is supportedhorizontally and defines a passageway through which the empty steel barrels are passed. A conveyer which is driven in any suitable manner is provided for carrying the barrels through the chamber at a predetermined speed to enable them to completely burn out. Gas jets are provided for starting the fire within the chamber, and an alternating series of oil nozzles spray oil into the chamber to keep the fire burning.

Novel means in the form of an adjustable air nozzle array is arranged to direct the air partly into the chamber as required to provide a recirculating action of the flame pattern and a fire of relatively low temperature. The cylindrical chamber is provided with an open slot along the full length of its upper surface over and through which the air stream is directed by a plurality of nozzles spaced along the length of the cylinder. By

adjusting the air streams partly into or out of the cylinder the flame may be kept clean and smoke-free. Sensors are provided to monitor combustion conditions and to actuate the various adjustable control devices hereinafter described and thus to stabilize and control combustion for smoke-free operation of the device.

Air curtains are provided at each end of the chamber so that the barrels may enter and leave the chamber with a minimum of smoke emission from these openings. An air lock could be provided with double doors at the entrance and exit openings to eliminate smoke emission and to minimize disturbance of the combustion process within the chamber.

12 Claims, 3 Drawing Figures PATENTEDAPR 2 5 m2 SHEET 2 OF 2 PM WPQHW,

fli'ior raey INCINERATOR BACKGROUND OF THE INVENTION The invention relates to incinerating apparatus particularly adapted for use in burning out barrels having a waste residue to enable the same to be used again wherein a novel flame pattern is provided which provides an efficient controlled burning of hydrocarbons and other combustibles, both within and outside the combustion chamber, to provide an economical incinerator producing relatively low temperatures, which is substantially smokeless. Adjustable air nozzles are arranged to control the combustion process, both within and outside the chamber, and to provide an ample air supply for complete combustion of the material being incinerated.

DESCRIPTION OF THE PRIOR ART In prior incinerators of which I am aware, air is blown down into a square combustion chamber having an open top. In this type of device, very high temperatures are generated, thus necessitating a combustion chamber lined with refractory material to prevent burning out of the incinerator walls. Further, in the incinerator of which I am aware, there is no accurate control of the combustion process. High velocity air is forced into the chamber and particulate matter can frequently be forced out into the atmosphere. It is particularly important to provide a smokeless incinerator process and apparatus, and the present invention provides such an incinerator.

SUMMARY OF THE INVENTION The presentinvention relates to a novel incinerator wherein provision is made for controlling the combustion of the material to be burned. To this end, a combustion chamber is provided which embodies a cylindrical configuration having an opening in its top surface, which opening may be widened or narrowed as desired. Adjustable air jets are provided and arranged to direct streams of air across the opening. Part of the air and burning gas in the air jet is diverted into the cylindrical chamber by the splitting action of the edge of the opening and causes the burning gases within to circulate circumferentially, thus causing the chamber to be completely filled with circulating flame. Any unburned particulate or gassy matter will be burned as it contacts and is forced up into the air jet above where high temperature conditions and a constant oxygen excess exist.

Fuel in the form of oil is fed into the chamber in the form of a spray and gas jets are provided to start the fire without smoke. The oil provides auxiliary fuel to feed the fire and provides continuous burning within the chamber.

In accordance with the invention, control of the incinerating process is maintained by varying the air pressure in the nozzle air supply, by varying the angle of the air stream relative to the opening, so that only as much of the flame and air is recirculated within the chamber as is necessary to maintain combustion and vaporization of the fuels within the chamber. The width of the opening may be varied to vary the radiation and mixing action of the jet to compensate for water content variation in fuels being burned. Waste and auxiliary fuel input may be varied to maintain constant and complete combustion.

Accordingly, the principal object of the invention is to pro vide a novel and improved, highly efficient incinerator whereby control of all parts of the combustion process are constantly maintained.

A further object is to provide an incinerator wherein a reducing and cracking action occurs at a constant temperature distribution within the chamber and overheating of the steel shell is prevented.

Another object of the present invention is to provide a reducing atmosphere whereby oxidation and scaling of the steel combustion chamber and of barrels being processed is prevented, as well as damage to any material handling equipment within the chamber, such as conveyors.

Still further object is to provide an incinerator particularly characterized by providing a long slow combustion path and process which is particularly adapted for efficiently burning waste material having a high water content. Therefore, this gives ample time for particulate matter, smoke, free carbon, droplets of unvaporized hydrocarbons and other unburned high water content material to be all completely vaporized and mixed, recirculating within the chamber before final mixing with the moderate velocity, large volume air jet where they are completely burned before passing out of the flame plume. The result is smoke-free incineration.

With these general objects in view and such others as may hereinafter appear, the invention consists in the present novel incinerator and in the various structures, arrangements and combinations of parts hereinafter described and particularly defined in the claims at the end of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings illustrating the preferred embodiment of the invention: 5

FIG. 1 is a plan view of the incinerator embodying the invention;

FIG. 2 is a cross sectional view taken on the line 2-2 of FIG. 1; and

FIG. 3 is a cross sectional view of the incinerator taken on the line 3-3 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring now to the drawings, in general, the illustrated in cinerator embodying the present invention as shown in FIGS. 1-3 comprises an elongated hollow steel cylinder 10 forming the shell of a combustion chamber indicated at 12. The cylinder 10 is preferably, and for purpose of illustration, 7 feet in diameter and approximately 50 feet in length, and defines an elongated combustion chamber 12. As shown, the cylinder is supported on a horizontal axis by supports 14 along its length and is provided along its length with a plurality of spaced reinforcing ribs 16.

The present incinerator is particularly adapted for use in burning out used steel drums or barrels which may have been filled with any variety of substances, such as, waxes, tars or resins, etc., to thereby clean the same.

In order to feed a supply of barrels 18 to the combustion chamber 12, a conveyer 20 is provided. for carrying the barrels through the chamber. While the conveyer 20 has been herein illustrated as comprising a plurality of rollers 22 on which the barrels are carried, it will be understood that any commercial conveyer may be used. The rollers 22 are driven in any suitable manner, not shown, to cause'the barrels to pass through the combustion chamber at a predetermined rate of speed, such that the barrels will be completely burned out upon passage through the combustion chamber. I have found that with a 50-foot chamber, a normal conveyer speed would be 2 to 6 feet per minute. The speed would be variable according to the length of the chamber. In addition to the barrel conveyer 20, an ash conveyer, not shown, is contemplated for removing ash from the bottom of the chamber. Any commercial dragtype conveyer may be used for this purpose.

In accordance with the invention, means for starting combustion and maintaining the same within the chamber 12 is provided in the form of a series of gas jets 24 connected to a source of supply of gas not shown. A series of oil nozzles 26 alternating with the gas jets are also provided for supplying sprays of oil fuel to maintain combustion within the chamber during the incineration process. The oil nozzles 26 are also connected to a source of oil supply not shown. Thus, in operation, the gas is turned on and ignited manually. After a short time, the oil is turned on and ignited from the gas flame as the oil sprays into the chamber and over the barrels.

It is important to control smoke emission through inlet and outlet ends 27, 28 of the steel cylinder 10, and to this end, air

curtains 30, 32 are provided at each end of the cylinder. Each curtain comprises a conduit 34 connected to a blower 35 to supply air under pressure surrounding the open end 36 of a boxlike structure 38 secured to each end of the cylinder as illustrated best in FIG. 2. A series of nozzles 39 spaced equally around the circumference of the opening provide a continuous curtain or wall of air across the opening. The wall of air burns the escaping heated gases from the chamber, but permits the barrels to be fed into the combustion chamber. While an air curtain has been described, it will be understood that an air lock may be used at each opening to completely control smoke emission and to prevent transient air from entering the combustion chamber. An elongated slot 40 is provided in the top of the steel cylinder and is provided with a series of slidable covers 42 such that the width of the opening may be varied, open or closed, as desired, in accordance with the combustion required for the particular material being incinerated. As shown, the covers are arranged to be manually operated. However, it will be understood that they may be arranged to be operated automatically in any preferred manner.

In accordance with the present invention, novel means is provided for controlling the combustion process both with and outside the combustion chamber, and to this end, a manifold 44 is supported adjacent to the upper portion of the steel cylinder 10 in spaced relation to the open slot 40. The manifold is supplied with a supply of air under pressure, relatively low pressure, of from 2 to 10 inches of water. Thus, the air delivered by the nozzles is in the above pressure range. The manifold is mounted in any suitable manner for rocking movement in clockwiseand counterclockwise directions. A plurality of air nozzles 46, from 3 to 8 inches in diameter, are connected to the manifold in spaced relation to its length and extend to a point adjacent to the slot 40 as best shown in FIG. 3. The nozzles are pivotally supported at 50 and are arranged tangent to the cylinder at the edge of the slot so that the air may be directed by the nozzles across the slot opening, The angle of the nozzles relative to the slot in the cylinder may be varied, depending on the combustion conditions within the combustion chamber. In practice, the nozzle angle relative to the horizontal plane across the top of the slot 40 may be varied from to 20 and a variation of about is normal. The edge 43 of the slot 40 opposite the air nozzles serves as a splitter" to either divert air and flame into the cylinder or to allow the flame plume to pass out into the surrounding space. A small change in the rotation of the manifold directs the air jet to any desired combination of these two flame paths. The splitting action of the far side of the opening 43 is an important and novel feature of the invention.

In order to direct the position of the air nozzles and consequently the air streams relative to the slot 40, a piston 54 is connected to the manifold, as shown in FIG. 3, and within a hydraulic cylinder 56 pivotally mounted at 58.

The cylinder 50 may be of any commercially available type and is provided with a supply of fluid under pressure through line 60, 62 connected to a source of fluid under pressure not shown. Thus, by permitting fluid to enter one side of the cylinder through line 60, the manifold is rocked in a clockwise direction and the air nozzle directed upwardly into the slot, thereby increasing the flow of air into the combustion chamber. Conversely, if fluid is permitted to enter the cylinder through line 62, the manifold is rocked in the other direction and the tangency of the nozzle varied to direct more air into the chamber.

One of the important features of the present invention resides in the circulation of the air and gases within the combustion chamber and, consequently, a circulating flame pattern occurs within the chamber.

The combustion process involved here consists of two main parts-a combustion chamber within which rotating air and partly burned fuel is thoroughly mixed and air-flame jets over the top of this chamber which are exposed to the rotating gas by an opening over which the air jets flow. The air jets serve to induce rotation within the chamber and to burn the thoroughly mixed gas as it increases in volume within the chamber because all of the gas .within this chamber is forced to pass through the air jets in its escape to the outside air.

The circulation causes the burning gases to be constantly recirculated in the combustion chamber and repeatedly subjected to the mixing action of the flame-heated air jets at the slot opening, and as the volume of gases in the chamber increases due to the vaporization and combustion of the waste material and auxiliary fuel input, together with the air input from the air nozzles, the increased volume of gas is forced up into the air jets to be mixed with an ample oxygen supply and burned in a plume of flame around the air jets.

After the combustion has been started, the combustion process is adjusted to obtain the most efficient smoke-free incineration of the material being burned, and thereafter the operation is arranged to be controlled automatically by automatic control mechanism. To this end, a series of sensors are provided. A set of flame sensors 66, 68 are mounted in spaced relation to each other and to the open slot 40 as shown in FIG. 3. Sensors 66 are positioned at the point spaced from the edge 43 of the slot 40 wherein a minimum acceptable flame plume should extend, and sensors 68 at a point defining the maximum flame plume.

The sensors may be of any commercial type found on the market and are arranged to be connected to a modulating pump or metering device to increase or decrease the amount of auxiliary oil fed into the combustion chamber, depending upon whether more or less flame is required. Auxiliary oil is necessary to the maintenance of an even fire, since normally, the material being burned will not in and of itself sustain the burning process. A plurality of chamber temperature sensors 70 are positioned in spaced relation within the chamber and comprise thermo couples of a type available on the market. The function of these sensors is to control the combustion chamber temperature.

Sensors 70 are connected to means for actuating the nozzle tilting mechanism. As the temperature within the chamber reaches a predetermined low degree, the sensor actuates the nozzle adjusting mechanism to cause it to be directed downwardly, thus causing more air and flame to be directed into the chamber, and consequently, the temperature will rise to the proper degree. Conversely, too high a chamber temperature causes the sensor to activate the mechanism to reduce the volume of air and flame into the chamber, and thus reduce the temperature and burning.

While the above described control mechanisms are preferred for controlling and regulating the burning process, it will be understood that other controls may be used for this purpose, and that devices for integrating all these functions can be incorporated.

In accordance with the present invention, the flame plume temperature at the slow may vary from 2,200 to 2,500 F., and preferably the combustion chamber temperature from 800 to 1,000 F.

The present invention embodies still another means of controlling the combustion process, i.e., to provide smokeless incineration and to this end, the slot 40 in the top of the combustion chamber is provided with movable covers 42 which may be closed or opened in varying degrees so that point 43 can be moved. The width of the slot has profound and complex bearing on the operation of the incinerator. These effects include:

1. Regulation of the length of the contact of the air-flame jet with rotating gas below in the combustion chamber and, consequently, of the mixing action of these two adjacent gas streams.

2. The width of the slot governs the amount of radiation of heat from the jets down into the chamber and of the heat in the chamber up to the sky.

3. The width of the slot governs the velocity of the gas stream moving from the chamber up into the air jets and the interaction of the air entering the chamber from the jets with the gas leaving the chamber.

In summary, the slot is a common meeting point of the two combustion paths of this device, and its width is critical to successful operation of the process. Taken together with the other adjustments, herein described, the flexibility of adjustment and the consequent complete control of the combustion within this device renders it capable of operating in a smokefree manner under a wide range of operating conditions.

From the foregoing description of the invention, it will be apparent that the present device provides an efiicient and economical incinerator having novel provisions for controlling the burning process whereby efficient incineration is accomplished, and at the same time, pollution of the atmosphere is substantially eliminated.

While the invention has been described as embodied in an incinerator, the device has applications as an oil burner for heating or power generation wherein fuel of high water content is used. The device may also be used to incinerate numerous materials, such as rubber tires, burning insulation from copper wires or burning out automobile bodies, and small or large scale commercial trash incineration.

The relatively low combustion chamber temperature permits an economical chamber to be used as refractory material to prevent burning out of the chamber is not required, and the arrangement for causing the recirculation and mixing of the combustion gases within the chamber results in highly efficient incineration.

It will be understood that the invention may be embodied in different forms within the scope of the following claims.

Having thus described the invention, what is claimed is:

1. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be; incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, said control means comprising a plurality of air nozzles connected to a source of air under pressure, said nozzles adapted to be raised or lowered tangentially relative to the opening in the top of the chamber.

2. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, said control means comprising a maximum and a minimum external flame sensor and a thermo couple within the combustion chamber.

3. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the tire, and control means for adjusting the air flow and and fuel supply to provide an even smoke-free fire, at.

least the upper portion of the combustion chamber being cylindrical.

4. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, one edge defining the opening in the top of the chamber dividing the air flow into an external flow and an internal flow.

5. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for pennitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, said means at each end of the combustion chamber comprising an air curtain.

6. An incinerator as defined in claim 3 wherein the external flame sensors are spaced from each other a predetermined distance.

7. An incinerator for burning waste material in a smoke-free manner comprising an elongated cylindrical open-ended com bustion chamber, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting waste material to be carried into and through the chamber, a conveyer for carrying the waste through the chamber, an elongated open slot in the upper surface of the combustion chamber and a cover for said slot, a plurality of vertically adjustable air nozzles connected to a supply of air under pressure mounted in spaced relation along one edge of the slot for providing a circulating pattern of air within the chamber and a flame pattern outside of the chamber, a fuel supply for the chamber and ignition means for igniting the incinerator.

8. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, said means for introducing air under pressure into the combustion chamber comprising a manifold connected to a supply of air under pressure and a plurality of nozzles connected in spaced relation along the manifold, the ends of said nozzle being disposed adjacent one edge of the opening in the top of the chamber and adjustable to direct more or less air into the chamber, depending upon whether or not more or less flame is required in the chamber.

9. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, hydraulic'means being provided for adjusting the manifold and nozzles vertically.

10. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through a said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, said means for preventing the escape of smoke for the combustion chamber comprising a rectangular enclosure mounted at each end of the chamber and having adjacent its open end a plurality of air jets connected to a supply of air under pressure to thereby provide a curtain of air across the open end of the enclosure whereby waste may be conveyed into, through and out of the chamber and smoke prevented from passing therethrough.

11. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, the air in the air jets and the circulating gases in the combustion chamber being brought into contact with each other in gradually merging and diverging parallel paths.

12. An incinerator as defined in claim 3 having configuration wherein the air in the air jets and the circulating gases in the combustion chamber are brought into contact with each other in gradually merging and diverging parallel paths, 

1. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smokefree fire, said control means comprising a plurality of air nozzles connected to a source of air under pressure, said nozzles adapted to be raised or lowered tangentially relative to the opening in the top of the chamber.
 2. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, said control means comprising a maximum and a minimum external flame sensor and a thermo couple within the combustion chamber.
 3. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and and fuel supply to provide an even smoke-free fire, at least the upper portion of the combustion chamber being cylindrical.
 4. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, one edge defining the opening in the top of the chamber dividing the air flow into an external flow and an internal flow.
 5. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, said means at each end of the combustion chamber comprising an air curtain.
 6. An incinerator as defined in claim 3 wherein the external flame sensors are spaced from each other a predetermined distance.
 7. An incinerator for burning waste material in a smoke-free manner comprising an elongated cylindrical open-ended combustion chamber, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting waste material to be carried into and through the chamber, a conveyer for carrying the waste through the chamber, an elongated open slot in the upper surface of the combustion chamber and a cover for said slot, a plurality of vertically adjustable air nozzles connected to a supply of air under pressure mounted in spaced relation along one edge of the slot for providing a circulating pattern of air within the chamber and a flame pattern outside of the chamber, a fuel supply for the chamber and ignition means for igniting the incinerator.
 8. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, said means for introducing air under pressure into the combustion chamber comprising a manifold connected to a supply of air under pressure and a plurality of nozzles connected in spaced relation along the manifold, the ends of said nozzle being disposed adjacent one edge of the opening in the top of the chamber and adjustable to direct more or less air into the chamber, depending upon whether or not more or less flame is required in the chamber.
 9. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, hydraulic means being provided for adjusting the manifold and nozzles vertically.
 10. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opeNing, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, said means for preventing the escape of smoke for the combustion chamber comprising a rectangular enclosure mounted at each end of the chamber and having adjacent its open end a plurality of air jets connected to a supply of air under pressure to thereby provide a curtain of air across the open end of the enclosure whereby waste may be conveyed into, through and out of the chamber and smoke prevented from passing therethrough.
 11. An incinerator for burning waste material comprising an elongated combustion chamber, a conveyer passing through said chamber for carrying material to be incinerated, means at each end of the chamber for preventing the escape of smoke from the chamber and for permitting the entrance of the material to be incinerated, an opening in the top of the chamber, a movable cover for said opening, means for introducing a flow of air into the interior of the chamber through the opening and for causing the air and gas mixture within the chamber to mix and recirculate within the chamber, ignition means for starting the incinerator, fuel supply means for feeding the fire, and control means for adjusting the air flow and fuel supply to provide an even smoke-free fire, the air in the air jets and the circulating gases in the combustion chamber being brought into contact with each other in gradually merging and diverging parallel paths.
 12. An incinerator as defined in claim 3 having configuration wherein the air in the air jets and the circulating gases in the combustion chamber are brought into contact with each other in gradually merging and diverging parallel paths. 